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Old 09-12-2003, 06:58 AM   #226
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Hi, any1 here have any comment on the Kyosho engin and the yokomo engin that come with the V1SII and the GT-4? which stock engin (V1SII and GT-4) is better? From the box stated, the yokomo one can up to 100 km/h, is it true? then how bout the V1SII?

Planning to get either 1 of these 2 car? Any comment? Their price are almost the same...
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Old 09-12-2003, 08:41 AM   #227
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Quote:
Originally posted by HELLION
I'm not implying that you are wrong 777 but there are allot of contingencies based on compression,running temp ect. But I do know this :allot of guys are under the false pretence do to the fact that when a engine starts to lose compression it gains rpm. The most important component in horsepower is torque and this is what you lose when a engine starts to lose compression . this can be proven on a dyno. You can have all the r.p.m.s you want but if your engine lacks torque.then you just reinvented the rubber band. I.E Lets say your engine has a max r.p.m output of 40,000 but your max powerband (torque) kicks out at 35,000. This simpley states that anything above 35,000 exceeds the power limit as the power of the motor diminishes after that point! This is why when you have a car tested on a dyno the test results will give you your highest horsepower and torque intersect readings so you know your maximum powerband
Hey Hellion thanks for replay.
Well I totaly disagree with you about the torq is related to compression direct. The first of all we are are talking about reasonble limits here, I never mentioned we don't need compressin, we need right amount of it. What we have today on all engines-manufacturers are making P/S sets too tight and it is realated to their technology, lack of right P/S materials and profit.
If you have right material set up (ABC, AAC and other combinations) and you make right fit in the P/S sets, first of all, your engine life will be 3 times longer, secondable it run cooler, third-you will not need that hours run in time. Let's say what is Silicon content in piston material for Novas today? It is about 15-18 %. What do you think will happen if we have 27 or even 32%. In short word-it will run much longer. So, if it has longer life what for I will do P/S set too tight ( BTW-tighter doesn't mean longer life, means-more stres on everything-P/S, conrod, piston material etc)?
About the torq, power band of the engine dictate not by compression, it mostly dictate by timing. If you want to make high torq engine, just do transfer 130 and exhaust 150, but if you want to low torq and high RPM do 140 transfer and 190 exhaust (induction has to be according resonble too).
In general, compression just dictate engine condition, but not realy dictate any power bands or performance.
So in my opinion, there are more variables which are affecting engine performance, then regular assumption, but not all of them under control on today situation, this is why I am on my way to produce my engine. Modding Novas will give us some gain, but overall it is dead end (performance, life, costs etc). I know these brands since 1977 and belive me, I "burn" a lot of them.
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Last edited by Top Gun 777; 09-12-2003 at 01:51 PM.
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Old 09-12-2003, 11:10 AM   #228
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hellion I don't think you will gain any more
power by having a really tight fitting
p/s fit. i would have to agree that the
power band is dictated by crank timing
port design and head clearance and other
factors. the piston and sleeve just need
to be at a certain tolerance just like with
real cars if you wanted to raise the compression
you would not make a really tight fitting piston
but would change to a higher compression
piston instead but the wall clearance should
be the same.
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Old 09-12-2003, 12:36 PM   #229
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I would have to agree with JWF_Frani on this one. My theory would be that compression is gained depending on the clearance between the button and top of the piston from when it starts to compress the mixture until it reaches TDC. Ad far as tight fitting P/S, I believe all this is doing is adding friction which is slowing the engine RPM and stopping the engine from producing those all important Top End Revs for longer tracks. Whats the point of squeezing the crap out of the sleeve with a really tight piston other than manufacturers trying to reduce the amount of usable power in production engines so that the main team drivers always have that elusive edge over the rest off the competition.
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Old 09-12-2003, 01:45 PM   #230
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Quote:
Originally posted by modellor
so that the main team drivers always have that elusive edge over the rest off the competition.
can I correct you? HAD, no have, they had before, now, everybody can have the same.
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Old 09-12-2003, 02:23 PM   #231
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Quote:
Originally posted by Top Gun 777
can I correct you? HAD, no have, they had before, now, everybody can have the same.
Ok, I stand correct. They HAD that elusive edge.
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Old 09-12-2003, 02:48 PM   #232
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wow..very nice stuff guys......


what a differnce from the usual "clown network" with nothing to say other threads.........

Hi Modellor.....

Top Gun,I'm going to call you on Monday....
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Old 09-12-2003, 03:01 PM   #233
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Let's keep it rolling!!!!!!!!!!!!!!
Some more topics and keep them rocking!!!
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Old 09-12-2003, 03:17 PM   #234
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I remeber that the Mugen MT12 engines from 3 years ago had an incredible tight fit, to a point where they would get stuck at TDC during break in on a regular basis.

I think we all can imagine what that does to a conrod during break in.

I know of several people that either had designated break in rods which they only put in the engine for break in or they changed the rod right after break in for a new one.

Also, these engines did get much faster once they wore in to a point where you could turn them over w/o a pair of channel locks.

Recently, replacement P/S for the MT12 are showing a much "looser" fit than in the past and these P/S's only take a fraction of the time to break in and they are just as fast.

I think we should in general keep two things seperate:

Pinch: The grinding, metal on metal scraping fit that a new engine has close to TDC

Compression: the ability of the P/S to seal the combustion chamber sufficiently to avoid the "blow-by" of the expanding combustion gases.

I don't think the latter doesn't completely depend on the first.

Just my $0.02
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Old 09-12-2003, 03:21 PM   #235
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Nova Rossi based????

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Old 09-12-2003, 03:26 PM   #236
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hey stafan..did you catch that link I put up to the castor oil?..
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Old 09-12-2003, 03:47 PM   #237
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Quote:
Originally posted by stefan
Nova Rossi based????


I think not, Heard last year that Steve O'Donnell was in catfight with RB for having direct access to raw materials from RB France without needing to pass by the US Distributor.

I Know that has flirted with Picco Bros in the recent past. But probably has returned to Nova Mills, Interesting to see how performs. There are many little details that remember me to Nova engines, but other details of the casting remembers me to Picco ones.

Any more details about this?
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Old 09-12-2003, 04:10 PM   #238
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Quote:
I would have to agree with JWF_Frani on this one. My theory would be that compression is gained depending on the clearance between the button and top of the piston from when it starts to compress the mixture until it reaches TDC. Ad far as tight fitting P/S, I believe all this is doing is adding friction which is slowing the engine RPM and stopping the engine from producing those all important Top End Revs for longer tracks
Absolute fact.

Its all about seal with the minimum friction possible, many piston and sleeve sets have been discarded just when they start getting good.
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Old 09-12-2003, 04:28 PM   #239
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Hi Dennis, how are your projects coming along
and when are coming down here again.
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Old 09-12-2003, 04:35 PM   #240
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Quote:
Originally posted by Motorman
Absolute fact.

Its all about seal with the minimum friction possible, many piston and sleeve sets have been discarded just when they start getting good.
Right to the money.
Very often racer just change the P/S, ones they think it going down, I saw how the condition was checked-they hold engine by the shaft and if it was folling down (turnig from vertical head up )-so thet P/S was not good.
But again, Motorman, Italins material still way behind where the best are.
I checked all possible materials from all engines by spectrum analosers and found everything very old, just SX model was closer to right ( in my opinion). As I mentioned before, there is only one available technology today to produce desired alloy, it is powder backing technology, so far not found in US.
With that alloys you can do a lot of stuff, without having friction issue. I do have access to it and latest development showing 32% have been reached, There are bunch others components there and will not list them here, too much and doesn't make sence at all, any way it not reachable jst by wishing.
My point is, if we want to move on, we nee to change our mind about compression issue and understand, there is more complictaed stuff have influence on engine performance.
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